We propose a 5-year prospective randomized trial of a theory-based intervention to increase compliance with mammography screening guidelines in female veterans 52 years of age and over. Specific aims of the project are to: 1) develop and evaluate the usefulness of an intervention based on the Transtheoretical Model (TTM) to increase compliance (completion of two mammograms) and coverage (completion of at least one mammogram) during the project; 2) analyze the relationship of a number of predictor variables with compliance and coverage; and 3) conduct a cost-effectiveness analysis of increasing compliance with mammography screening recommendations. We will randomly sample 7,500 women 52 years of age and over from the National Registry of Women Veterans (NRWV), a computerized database including 1.5 of the estimated 1.5-1.8 million women veterans separated from active military duty since January 1, 1942. Participants will be randomized to one of five groups. Groups 1 and 2 will be used to evaluate a targeted (aimed at an individual's stage of change) vs. a targeted and tailored (inclusion of personalized feedback) intervention. Groups 1 and 2 will receive an educational booklet based on the TTM. Group 1 also will receive a tailored feedback letter based on responses to a survey that measures constructs from the TTM (e.g., decisional balance, processes of change), as well as constructs from other behavior change models, while group 2 will receive a generic letter encouraging screening. There will be two rounds of the intervention for groups 1 and 2. Groups 3, 4, and 5 are control groups that will receive only the survey(s). Group 3 will be the primary control group against which we will measure the effect of the intervention; groups 4 and 5 will be used to evaluate secular trends and measurement effects of the surveys. Project materials will be mailed, and nonrespondents will be followed up by telephone. Mammography screening status will be ascertained by self-report, and a validation study will be conducted of the outcome measure. At this point, we know very little about how to get women to maintain regular mammography screening or about its cost-effectiveness. The few studies that have been conducted, or that are in progress, have focused on efficacy. The proposed research will evaluate the effectiveness of a sustained intervention to increase regular mammography in a nationally representative, well-defined population of women. The infrastructure is in place to institutionalize the intervention should it prove to be effective.